Leishmaniasis is a protozoal parasitic disease transmitted by sandflies and found in the tropics, subtropics, and southern Europe. The most common forms of the leishmaniasis are cutaneous (skin) and visceral (organs including spleen, liver, and bone marrow). The disease affects millions of people worldwide. Sandflies carrying the promastigote form of the parasite bite a human host, attracting macrophages to the site of the wound. Promastigotes are then phagocytized by the macrophages, transform into amastigotes and multiply within the macrophage and various species-specific tissues. Sandflies are infected by amastigotes during feeding, and the amastigotes transform into the promastigote form in the sandfly gut, continuing the infection cycle.
Current treatments for leishmaniasis include sodium stibogluconate (SSG), amphotericin B (conventional and lipid formulations), pentamidine isethionate, miltefosine, ketoconazole, itraconazole, and fluconazole. However, these therapies result in significant side effects. Side effects of SSG treatment, for example, include phlebotoxicity and pancreatitis. Amphotericin B's side effects include high fever, shaking chills, hypotension, anorexia, nausea, vomiting, headache, dyspnea and tachypnea, drowsiness, and generalized weakness. Thus, new therapies that can replace or reduce the dose of conventional therapies are desirable.